Is the name of the login being added to the fixed server role. login is sysname, with no default. login can be a SQL Server login or a Windows login. If the Windows login has not already been granted access to SQL Server, access is automatically granted.
[ @rolename = ] 'role'
Is the name of the fixed server role to which the login is being added. role is sysname, with a default of NULL, and must be one of the following values: